Ultra-Compact Raman

Spectrometer for Planetary

Explorations

Team

Derek Davis

Computer Engineering, Electrical Engineering

In collaboration with:

James Hornef (ECE 487 senior design team)

John Lucas (ECE 487 senior design team)

Faculty Adviser:

Dr. Hani Elsayed-Ali

NASA Adviser: Dr. M Nurul Abedin

Objective

To develop a compact Raman spectroscopy system

with features that will make it suitable for future

space missions which require surface landing.

Specifically, this system will be appropriate for any

mission in which planetary surface samples need to

be measured and analyzed.

What is Raman Spectroscopy?

When light hits matter, how does it react?

Absorbed

Reflected

Scattered

What is Raman Spectroscopy?

Scattered Light

Determined by properties of target

Unique “fingerprint” for different molecules

Note: Not all materials create Raman

scattered signals

What is Raman Spectroscopy?

Raleigh Scattered

Example of photon behavior when hitting polarizable material

What is Raman Spectroscopy?

Example Raman spectra of (a) water, and (b) ice [2]

Recap: Raman Spectroscopy

Powerful technique for detecting both organic

and inorganic materials inside of a sample

material

Uses lasers to excite and vibrate molecules

inside of unknown material

Vibrational pattern of material can be

measured to identify molecular composition

Spectrometer

Device that takes in light and disperses it into its

component wavelengths

Uses:

Carbon Dating

Respiratory gas analysis

protein characterization

Raman Spectroscopy

Realistic Constraints

Lightweight, small footprint, for installation on planetary rovers

Ability to measure samples within a range of < 20 cm with no

physical samples taken

Ability to operate in bright light (daytime), and low light

(nighttime) environments

Ability to detect water, biological, and organic compounds

Ability to detect all minerals, regardless of physical appearance

(light / dark)

Ability to detect Raman signals in the presence of fluorescence

Design Approach

Block diagram of proposed system using a laser,

neutral density filter (ND), a 45° mirror (P1), notch

filters (NF1, NF2), A 20x magnification microscope

objective (20x M), a slit (S1), achromatic lenses (L1,

L2) a volume phase holographic grating (HG), and a

mini ICCD camera.

Spectrometer

Laser

Nd:YAG (Neodymium-Doped Yttrium Aluminum Garnet;

Nd:Y3Al5O12), diode pumped, Q-switched Laser

model number QL532-500. Manufactured by Crystal

Laser LC, this 532nm 500 mW laser will be operating at a

switched rate of 1 kHz.

Spectrometer

ND: Neutral Density Filter

Lowers the intensity of the output laser without

affecting the wavelength

Protects back end optics from damage

Spectrometer

NF1: Dichroic 532nm Mirror

Reflects 90% of 532nm light while passing other

wavelengths

NF2: 532nm Notch Filter

Filters remaining 532nm light

Spectrometer

20x M: Microscope Objective

Intensifies captured Raman signal. Allows the

spectrometer to capture and analyze weak signals.

Spectrometer

S1: 50µm Slit

Determines the amount of light that is allowed into the

spectrometer

Setting the Slit focal length

Lost signal

Full signal

Example of (a), incorrect length and

(b) correct focal length

Spectrometer

L1: Focusing Lens

5mm achromatic doublet

1 cm focal length

Maximizes signal intensity into the holographic

grating.

Spectrometer

HG: Holographic Grating

Transmission grating with angles of incidence and

transmission of 45°

Splits incoming light into component wavelengths

2x Fused gratings

Output from grating

Output of grating using all visible light

Spectrometer

L2: Collection Lens

10mm achromatic doublet

3 cm focal length

Captures light spectrum generated by the

holographic grating and directs it into the ICCD

Choosing a collection lens

(a) Reflective grating with 5mm collection lens capturing full spectrum,

(b) Transmission grating with 5mm collection lens capturing partial

spectrum, and (c) Transmission grating with 1in collection lens

capturing full spectrum.

Spectrometer

ICCD

Captures the image from the collection lens and

converts it into a digital image

2048 X 2048 pixel resolution

Prototype System

Laser aligned breadboard system

8.79cm x 2.03cm

Prototype System

Engineering Standards

ASNI Z136.1-2007: The American Nation Standard for Safe Use of Lasers

NASA-STD-(I)-0007 NASA Computer-Aided Design Interoperability

NASA-STD 8739.6 Implementation Requirements for NASA Workmanship

Standards

IEEE 1394-2008 IEEE Standard for a High-Performance Serial Bus

ExpressCard 2.0 Standard

References1. S. Sharma, A. Misra and P. Lucey, "A combined remote Raman and fluorescence

spectrometer system for detecting inorganic and biological materials", Lidar Remote

Sensing for Environmental Monitoring VII, 2006.

2. N. Abedin, et al., “Compact remote multi-sensing instrument for planetary surfaces and

atmospheres characterization”, Applied Optics, vol. 52, pp. 3116-3126, 2013.

3. C. Walker, "Spectrometer Technology and Applications", Azom.com, 2013. [Online].

Available: http://www.azom.com/article.aspx?ArticleID=10245. [Accessed: 26- Mar-

2016].

4. ASNI Z136.1-2007, 1st ed. Orlando, Fla.: Laser Institute of America, 2015, pp. 1-81. [PDF]

Available: https://www.lia.org/PDF/Z136_1_s.pdf [Accessed: 20-Mar- 2016]

5. NASA-STD-(I)-0007 NASA COMPUTER-AIDED DESIGN INTEROPERABILITY, 1st ed. Washington,

DC: National Aeronautics and Space Administration, 2009.

6. NASA-STD 8739.6 IMPLEMENTATION REQUIREMENTS FOR NASA WORKMANSHIP STANDARDS,

1st ed. Washington, DC: National Aeronautics and Space Administration, 2012.

7. IEEE Std 1394™-2008: IEEE Standard for a High-Performance Serial Bus, 1st ed. New York,

NY: IEEE-SA Standards Board, 2008.

8. ExpressCard Standard 2.0, 1st ed. San Jose, CA: PCMCIA, 2009.